A stethoscope is used to amplify body-borne sounds sent from a human or animal heart, lung, stomach, etc., as a means of diagnosis. Using a stethoscope, the listener can hear normal and abnormal respiratory, cardiac, pleural, arterial, venous, uterine, fetal and intestinal sounds. Most stethoscopes have the following parts: eartips, eartube, tubing, headset, stem, chest-piece, diaphragm, and a bell. Sounds from the body are passively amplified and transmitted to an air volume via the bell or a diaphragm. The diaphragm mechanism is preferred for most diagnostic applications.
The diaphragm is normally a thin structure typically made of flat or curvilinear-formed plastic material with some means of creating axial compliance so that it can have motion. When the diaphragm is pressed to the patient's flesh, it will move due to body-generated pressures. The diaphragm is air-sealed to an enclosed or captive air volume which has a small hole in it leading to air tubes. The diaphragm's motion changes the volume of captive air, thus creating an acoustic signal at the exit hole that enters the air tubes. The resulting acoustic signals are then sent via the tube assembly to the stethoscope operator's ears.
There have been numerous studies that indicate that stethoscopes transmit infectious agents between patients and are a source of healthcare associated infections.1 Many show that the contamination level of the stethoscope is substantial after a single physical examination. While healthcare workers are mandated to wash or otherwise sanitize their hands after patient contact, there are currently no guidelines that require stethoscopes be sanitized after every use. The diaphragm is the part of the stethoscope that maintains the most contact with the patient. As such, it would be useful for stethoscope diaphragms to be constructed from materials that are known to be antimicrobial in nature, such as copper and copper alloys, and still retain their acoustic-transduction properties. 1https://www.+news-medical.ne-Vne.vs/20170511+:New-study-reveals-8025-of-stethoscopes-are-contaminated-with-infectious-bacteria.aspx (accessed Mar. 1, 2018) (discussing a study performed by the American Journal of Infection Control revealing that “80 percent of the stethoscopes they studied were contaminated by high concentrations of bacteria.”)